I have the following c# code to generate a digital signature from a private key:
static string Sign(string text, string certificate)
{
X509Certificate2 cert = new X509Certificate2(certificate, "TestPassword", X509KeyStorageFlags.Exportable);
RSACryptoServiceProvider rsa = (RSACryptoServiceProvider)cert.PrivateKey;
// Hash the data
SHA1Managed sha1 = new SHA1Managed();
ASCIIEncoding encoding = new ASCIIEncoding();
byte[] data = encoding.GetBytes(text);
byte[] hash = sha1.ComputeHash(data);
// Sign the hash
return System.Convert.ToBase64String(rsa.SignHash(hash, CryptoConfig.MapNameToOID("SHA1")));
}
I then created what I thought was the equivalent java code:
public static String signData(String dataToSign, String keyFile) {
FileInputStream keyfis = null;
try {
keyfis = new FileInputStream(fileName);
KeyStore store = KeyStore.getInstance("PKCS12");
store.load(keyfis, "TestPassword".toCharArray());
KeyStore.PrivateKeyEntry pvk = (KeyStore.PrivateKeyEntry)store.
getEntry("testkey",
new KeyStore.PasswordProtection("TestPassword".toCharArray()));
PrivateKey privateKey = (PrivateKey)pvk.getPrivateKey();
byte[] data = dataToSign.getBytes("US-ASCII");
MessageDigest md = MessageDigest.getInstance("SHA1");
byte[] hashed = md.digest(data);
Signature rsa = Signature.getInstance("SHA1withRSA");
rsa.initSign(privateKey);
rsa.update(data);
return Base64.encode(rsa.sign());
} catch (Exception ex) {
Logger.getLogger(this.getClass().getName()).log(Level.SEVERE, null, ex);
} finally {
if ( keyfis != null ) {
try { keyfis.close() } catch (Exception ex) { keyfis = null; }
}
}
return null;
}
Unfortunately the digital signatures do not match.
Any assistance will be greatly appreciated.
Thanks in advance.
EDIT: If I remove the MessageDigest from the java code then the output is the same. Why? I thought hashing is needed.
Regards,
Eugene
The Java sign method does hashing and signing based on the algorithms provided in getInstance method of the Signature class, so basically you were hashing twice in Java.
Ok so I have confirmed it. If I remove the MessageDigest/Hashing code from the java sample code then the two digital signatures are the same. Not sure why, but I'll try and find out.
If anyone would like to educate me further feel free.
Related
I wrote two methods for signing using RSA and SHA256, the first one with OpenSSL library and the second one with Microsoft Cryptography library.
OpenSSL implementation:
private string PasswordHandler(bool verify, object userdata)
{
return userdata.ToString();
}
private string Sign(string signParams)
{
var privateCertPath = HttpContext.Current.Server.MapPath(#"~\certificate.pem");
string privateKey;
using (StreamReader sr = new StreamReader(privateCertPath))
{
privateKey = sr.ReadToEnd();
}
OpenSSL.Crypto.RSA rsa = OpenSSL.Crypto.RSA.FromPrivateKey(new BIO(privateKey), PasswordHandler, _password);
//hash method
MessageDigest md = MessageDigest.SHA1;
BIO b = new BIO(signParams);
CryptoKey ck = new CryptoKey(rsa);
byte[] res1 = MessageDigestContext.Sign(md, b, ck);
return Uri.EscapeDataString(System.Convert.ToBase64String(res1));
}
Cryptography implementation:
private string Sign(string data)
{
var privateCertPath = HttpContext.Current.Server.MapPath(#"~\certificate.pfx");
X509Certificate2 privateCert = new X509Certificate2(privateCertPath, _password, X509KeyStorageFlags.Exportable);
RSACryptoServiceProvider privateKey = (RSACryptoServiceProvider)privateCert.PrivateKey;
RSACryptoServiceProvider privateKey1 = new RSACryptoServiceProvider();
privateKey1.ImportParameters(privateKey.ExportParameters(true));
// Get the bytes to be signed from the string
var bytes = System.Text.Encoding.UTF8.GetBytes(data);
//const string sha256Oid = "2.16.840.1.101.3.4.2.1";
//HashAlgorithm algorithm = new SHA256CryptoServiceProvider();
//byte[] hashBytes = algorithm.ComputeHash(bytes);
//byte[] signature = privateKey1.SignHash(hashBytes, sha256Oid);
byte[] signature = privateKey1.SignData(bytes, "SHA256");
// Base 64 encode the sig so its 8-bit clean
return Convert.ToBase64String(signature);
}
Signing with OpenSSL works, generates valid digital signature but signing with Cryptography lib generates invalid signature so my question is what I implemented wrong?
I tried to use different encoding but it did not help. Certificates are generated correctly.
It might by also useful to tell basic info about the .pem certificate:
-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC
I'm quite new to all this encryption thing and I'm trying to do a simple app to encrypt a given string. Here's my code:
public static X509Certificate2 getPublicKey()
{
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
X509Certificate2 cert2 = new X509Certificate2("c:\\certificate.cer");
return cert2;
}
public static string cipherRequest(byte[] stringToEncrypt)
{
X509Certificate2 certificate = getPublicKey();
RSACryptoServiceProvider rsa = certificate.PublicKey.Key as RSACryptoServiceProvider;
byte[] cryptedData = rsa.Encrypt(stringToEncrypt, true);
return Convert.ToBase64String(cryptedData);
}
public static void Main()
{
try
{
ASCIIEncoding ByteConverter = new ASCIIEncoding();
byte[] test = ByteConverter.GetBytes("stringtoencrypt");
string first = cipherRequest(test);
string second= cipherRequest(test);
Console.WriteLine("first: {0}", first);
Console.WriteLine("second: {0}", second);
}
catch(CryptographicException e)
{
Console.WriteLine(e.Message);
}
}
So every time I call the cipherRequest it produces different results. I've checked the certificate is loaded but it produces different results.
Any thoughts?
Random padding is added before the actual encryption to avoid certain attacks. This is why you are getting different results each time you call the encryption method.
For more info, see this post:
RSA in C# does not produce same encrypted string for specific keys?
I am attempting to verify an OpenSSL signature (created using openssl_sign with SHA1 in PHP) using C# RSACryptoProvider.VerifyData. It is returning false using the correct public key certificate.
Any idea about how to do this successfully?
EDIT:
I attempted to verify the OpenSSL SHA1 signature using BouncyCastle with the following code but verification is failing. Are the signatures calculated differently? How can I create a signature with OpenSSL that is verifiable by .NET?
byte[] signatureBytes = UTF8Encoding.Default.GetBytes(signature);
byte[] dataBytes = UTF8Encoding.Default.GetBytes(data);
StreamReader sr = new StreamReader(Path.Combine(#"C:\test", #"test\test.crt"));
PemReader pr = new PemReader(sr);
Org.BouncyCastle.X509.X509Certificate cert = (Org.BouncyCastle.X509.X509Certificate)pr.ReadObject();
ISigner sig = SignerUtilities.GetSigner("SHA1WithRSAEncryption");
sig.Init(false, cert.GetPublicKey());
sig.BlockUpdate(dataBytes, 0, dataBytes.Length);
if (sig.VerifySignature(signatureBytes)) {
Console.WriteLine("all good!");
}
PHP Code:
function signTokenWithPrivateKey($message, $keyLocation) {
try {
if (file_exists($keyLocation)) {
$privateKey= openssl_get_privatekey(file_get_contents($keyLocation));
$signature = '';
if (!openssl_sign($message, $signature, $privateKey)) {
die('Failed to encrypt');
}
openssl_free_key($privateKey);
}
}
catch (Exception $ex) {
}
return $signature;
}
The following code should do the trick for you.
It loads the certificate from the file path given and then uses the public key to verify the data against the given signature. Returns true if valid.
byte[] signature = Convert.FromBase64String(Signature);
byte[] data = Encoding.UTF8.GetBytes(Data);
var x509 = new X509Certificate2(Path.Combine(#"C:\test", #"test\test.crt"));
var rsa = x509.PublicKey.Key as RSACryptoServiceProvider;
if (rsa == null)
{
LogMessage("Authorize", "Invalid", Level.Alert);
return false;
}
string sha1Oid = CryptoConfig.MapNameToOID("SHA1");
//use the certificate to verify data against the signature
bool sha1Valid = rsa.VerifyData(data, sha1Oid, signature);
return sha1Valid;
I'm trying to encrypt and decrypt data using RSA in C#. I have the following MSTest unit test:
const string rawPassword = "mypass";
// Encrypt
string publicKey, privateKey;
string encryptedPassword = RSAUtils.Encrypt(rawPassword, out publicKey, out privateKey);
Assert.AreNotEqual(rawPassword, encryptedPassword,
"Raw password and encrypted password should not be equal");
// Decrypt
string decryptedPassword = RSAUtils.Decrypt(encryptedPassword, privateKey);
Assert.AreEqual(rawPassword, decryptedPassword,
"Did not get expected decrypted password");
It fails during decryption, but only sometimes. It seems like whenever I set breakpoints and step through the test, it passes. This made me think perhaps something wasn't finishing in time for decryption to occur successfully, and me slowing stepping through it while debugging gave it enough time to complete. When it fails, the line it seems to fail at is decryptedBytes = rsa.Decrypt(bytesToDecrypt, false); in the following method:
public static string Decrypt(string textToDecrypt, string privateKeyXml)
{
if (string.IsNullOrEmpty(textToDecrypt))
{
throw new ArgumentException(
"Cannot decrypt null or blank string"
);
}
if (string.IsNullOrEmpty(privateKeyXml))
{
throw new ArgumentException("Invalid private key XML given");
}
byte[] bytesToDecrypt = ByteConverter.GetBytes(textToDecrypt);
byte[] decryptedBytes;
using (var rsa = new RSACryptoServiceProvider())
{
rsa.FromXmlString(privateKeyXml);
decryptedBytes = rsa.Decrypt(bytesToDecrypt, false); // fail here
}
return ByteConverter.GetString(decryptedBytes);
}
It fails with this exception:
System.Security.Cryptography.CryptographicException: Bad Data
My Encrypt method is as follows:
public static string Encrypt(string textToEncrypt, out string publicKey,
out string privateKey)
{
byte[] bytesToEncrypt = ByteConverter.GetBytes(textToEncrypt);
byte[] encryptedBytes;
using (var rsa = new RSACryptoServiceProvider())
{
encryptedBytes = rsa.Encrypt(bytesToEncrypt, false);
publicKey = rsa.ToXmlString(false);
privateKey = rsa.ToXmlString(true);
}
return ByteConverter.GetString(encryptedBytes);
}
The ByteConverter used throughout is just the following:
public static readonly UnicodeEncoding ByteConverter = new UnicodeEncoding();
I've seen a few questions on StackOverflow about RSA encryption and decryption with .NET. This one was due to encrypting with the private key and trying to decrypt with the public key, but I don't think I'm doing that. This question has the same exception as me, but the selected answer was to use OpenSSL.NET, which I would prefer not to do.
What am I doing wrong?
Could you replace ByteConverter.GetBytes with Convert.FromBase64String and replace ByteConverter.GetString with Convert.ToBase64String and see if that helps. Bad Data exception usually means that you have an invalid character in the data or that the length is not the correct length for decrypting. I think using the Convert functions might fix your problems.
public static readonly UnicodeEncoding ByteConverter = new UnicodeEncoding();
public static string Encrypt(string textToEncrypt, out string publicKey,
out string privateKey)
{
byte[] bytesToEncrypt = ByteConverter.GetBytes(textToEncrypt);
byte[] encryptedBytes;
using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
{
encryptedBytes = rsa.Encrypt(bytesToEncrypt, false);
publicKey = rsa.ToXmlString(false);
privateKey = rsa.ToXmlString(true);
}
return Convert.ToBase64String(encryptedBytes);
}
public static string Decrypt(string textToDecrypt, string privateKeyXml)
{
if (string.IsNullOrEmpty(textToDecrypt))
{
throw new ArgumentException(
"Cannot decrypt null or blank string"
);
}
if (string.IsNullOrEmpty(privateKeyXml))
{
throw new ArgumentException("Invalid private key XML given");
}
byte[] bytesToDecrypt = Convert.FromBase64String(textToDecrypt);
byte[] decryptedBytes;
using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
{
rsa.FromXmlString(privateKeyXml);
decryptedBytes = rsa.Decrypt(bytesToDecrypt, false); // fail here
}
return ByteConverter.GetString(decryptedBytes);
}
Your problem is with the conversion from bytes to string. Not all sequences of bytes are a valid UTF-16 encoding and you are using a UnicodeEncoding that silently ignores invalid bytes. If you used
public static readonly UnicodeEncoding ByteConverter = new UnicodeEncoding(false, false, true);
instead, your code would have failed when trying to convert the bytes instead of silently replacing the invalid byte-pairs with 0xFFFD.
The fact that the test worked while debugging was a coincidence. You are using a random RSA key-pair, so sometimes you will get a encryption that is a valid UTF-16 encoding.
The fix is, as SwDevMan81 suggests, to use an encoding that can convert all possible byte-arrays. F.x. Base64-encoding.
I would recommend using this class, sadly I don't remember the original author though..
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
namespace Encryption
{
class AsymmetricED
{
private static RSAParameters param = new RSAParameters();
/// <summary>
/// Get Parameters
/// </summary>
/// <param name="pp">Export private parameters?</param>
/// <returns></returns>
public static RSAParameters GenerateKeys(bool pp)
{
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
if (param.Equals(new RSAParameters()))
{
param = RSA.ExportParameters(true);
}
RSA.ImportParameters(param);
return RSA.ExportParameters(pp);
}
static public byte[] RSAEncrypt(byte[] DataToEncrypt, RSAParameters RSAKeyInfo, bool DoOAEPPadding)
{
try
{
//Create a new instance of RSACryptoServiceProvider.
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
//Import the RSA Key information. This only needs
//toinclude the public key information.
RSA.ImportParameters(RSAKeyInfo);
//Encrypt the passed byte array and specify OAEP padding.
//OAEP padding is only available on Microsoft Windows XP or
//later.
return RSA.Encrypt(DataToEncrypt, DoOAEPPadding);
}
//Catch and display a CryptographicException
//to the console.
catch (CryptographicException e)
{
Console.WriteLine(e.Message);
return null;
}
}
static public byte[] RSADecrypt(byte[] DataToDecrypt, RSAParameters RSAKeyInfo, bool DoOAEPPadding)
{
try
{
//Create a new instance of RSACryptoServiceProvider.
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
//Import the RSA Key information. This needs
//to include the private key information.
RSA.ImportParameters(RSAKeyInfo);
//Decrypt the passed byte array and specify OAEP padding.
//OAEP padding is only available on Microsoft Windows XP or
//later.
return RSA.Decrypt(DataToDecrypt, DoOAEPPadding);
}
//Catch and display a CryptographicException
//to the console.
catch (CryptographicException e)
{
ConsoleColor col = Console.BackgroundColor;
Console.BackgroundColor = ConsoleColor.Red;
Console.WriteLine(e.ToString());
Console.BackgroundColor = col;
return null;
}
}
}
}
Use as:
Encryption.AsymmetricED.RSAEncrypt(Data, GenerateKeys(false), false);
Encryption.AsymmetricED.RSADecrypt(Data, GenerateKeys(true), false);
EDIT:
I also recommend that you don't use this for large data encryption. Usually you would encrypt the actual data with a symmetric algorithm (AES, etc), then encrypt the symmetric key (randomly generated) with the RSA algorithm, then send the rsa encrypted symmetric key, and the symmetric key data..
You should also look at RSA signing, to make sure the data is coming from where it says it is..
I am using this function which I pulled off MSDN
static public byte[] RSAEncrypt(byte[] DataToEncrypt, RSAParameters RSAKeyInfo, bool DoOAEPPadding)
{
try
{
byte[] encryptedData;
//Create a new instance of RSACryptoServiceProvider.
using (RSACryptoServiceProvider RSA = new RSACryptoServiceProvider())
{
//Import the RSA Key information. This only needs
//toinclude the public key information.
RSA.ImportParameters(RSAKeyInfo);
//Encrypt the passed byte array and specify OAEP padding.
//OAEP padding is only available on Microsoft Windows XP or
//later.
encryptedData = RSA.Encrypt(DataToEncrypt, DoOAEPPadding);
}
return encryptedData;
}
//Catch and display a CryptographicException
//to the console.
catch (CryptographicException e)
{
Console.WriteLine(e.Message);
return null;
}
}
I am calling the method from here:
using (RSACryptoServiceProvider RSA = new RSACryptoServiceProvider())
{
//Pass the data to ENCRYPT, the public key information
//(using RSACryptoServiceProvider.ExportParameters(false),
//and a boolean flag specifying no OAEP padding.
encryptedData = RSAEncrypt(dataToEncrypt, RSA.ExportParameters(false), false);
But I am getting this error message:
Key not valid for use in specified state.
Any ideas what is going wrong?
The code works fine!! I tried it, I think you may have a problem in decryption as you should use the same keys
Unfortunately i have no idea about your Rsa problem but you may want to try this from here , which i use for a long time.
public static string Encrypt(this string stringToEncrypt, string key)
{
if (string.IsNullOrEmpty(stringToEncrypt))
{
throw new ArgumentException("An empty string value cannot be encrypted.");
}
if (string.IsNullOrEmpty(key))
{
throw new ArgumentException("Cannot encrypt using an empty key. Please supply an encryption key.");
}
System.Security.Cryptography.CspParameters cspp = new System.Security.Cryptography.CspParameters();
cspp.KeyContainerName = key;
System.Security.Cryptography.RSACryptoServiceProvider rsa = new System.Security.Cryptography.RSACryptoServiceProvider(cspp);
rsa.PersistKeyInCsp = true;
byte[] bytes = rsa.Encrypt(System.Text.UTF8Encoding.UTF8.GetBytes(stringToEncrypt), true);
return BitConverter.ToString(bytes);
}
You can also find Decrypt Extension there. I hope it'll help.